/Engine/Source/Editor/WorldBrowser/Public/IWorldTreeItem.h
Called to drop the specified objects on this item. Only called ifValidateDrop()allows.
void OnDrop ( const [FDragDropEvent](API\Runtime\SlateCore\Input\FDragDropEvent) & DragEvent, [TSharedRef](API\Runtime\Core\Templates\TSharedRef)< SWorldHierarchyImpl > Hierarchy )